Aside from the exclusiveness of the whole thing, there are reasons that Trappist beers aren't all shipped across the pond, and then across an entire continent.
While I don't doubt the abilities of the brewmasters to make an excellent, viable product, beer simply doesn't survive trans-atlantic voyages too terribly well - this was, as the story goes, the reason for the rise of the IPA. Heat/cold cycles, excess motion, and all of the horrors of transporting beer over long distances have incredibly deleterious effects on the quality.
@Arthur D and @Ken Graham are spot-on, and I would add to what they say; trust that the brewery knows best, in this case. You're on the west coast? There are some great monastic beers available from the Abbey of New Clairveaux (sp?), and you might be able to get Spencer occasionally.
But, really... why not take a world beer trip? I heartily recommend Belgium. The beer is second to none.